Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-06-07
2001-06-26
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S245000, C510S254000, C510S255000, C510S420000, C510S422000, C134S002000, C134S003000, C134S040000, C134S041000
Reexamination Certificate
active
06251847
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The invention relates to a process for cleaning and/or degreasing metal surfaces, particularly aluminum and aluminum alloy metal surfaces, still more particularly those used for heat exchangers.
2. Statement of Related Art
Many mechanical operations such as stamping, cutting, welding, grinding, drawing, machining, and polishing are used in the metal working industry to provide shaped metal articles. In metal working operations, lubricants, antibinding agents, machining coolants and the like are normally utilized to prevent binding and sticking of the tools to the metal articles in the various metal working operations. The lubricants, coolants, and antibinding agents and the additives present in these compositions usually leave an oily, greasy, and/or waxy residue on the surface of the metal which has been worked. The residue normally should be removed before the worked articles are given a protective surface finish or incorporated into a finished assembly. Other kinds of soil, such as particulate metal salts dried on from a rinse water supply, or the like also may adhere to metal objects and need to be removed by cleaning that is not strictly “degreasing”. Ordinarily, a single process that will remove all kinds of soil is desired; such a process is described herein as “cleaning/degreasing”.
A wide variety of aqueous cleaners usually combining alkaline inorganic salts with surfactants have been known for this purpose. None has proved to be fully satisfactory for use on composite objects containing both copper elements and aluminum elements, which are frequently used in automotive radiators and some other heat exchanging equipment. Alkaline cleaners, if sufficiently strongly alkaline to clean at a practically satisfactory speed normally must be inhibited with silicate to prevent unwanted dissolution of at least one of the underlying metals, but the silicate often leaves a residue that interferes with subsequent brazing operations required to join the cleaned parts into a suitable finished assembly. Acidic cleaners only rarely excessively dissolve aluminum or copper, but in order to clean aluminum at a practical speed normally contain metal chelating agents such as citric acid, ethylenediaminetetraacetic acid, or nitrilotriacetic acid; these have been found to chelate substantial amounts of copper from copper surfaces exposed to them during cleaning, and the copper can not usually lawfully be discharged into effluent water so that expensive pollution abatement measures are required.
DESCRIPTION OF THE INVENTION
Object of the Invention
A major object of the invention is to provide a water-based liquid cleaner that is capable of satisfactorily cleaning/degreasing normally fabricated metal articles, especially those made of aluminum alloys containing substantial amounts of copper, at speeds at least as high as those of currently used cleaners, while reducing pollution problems and not adversely affecting subsequent joining processes. Other objects are to provide a more economical process, a faster process and/or one requiring less expensive equipment for operation on a large scale.
General Principles of Description
Except in the claims and the operating examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, throughout the specification and claims, unless expressly stated to the contrary: percents, “parts of”, and ratio values are by weight; the term “polymer” includes “oligomer”, “copolymer”, “terpolymer”, and the like; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of electrically neutral constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description and/or by generation in situ by reactions described in the specification between already present and newly added material(s), and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; specification of materials in ionic form implies the presence of sufficient counterions to produce electrical neutrality for the composition as a whole (any counterions thus implicitly specified should preferably be selected from among other constituents explicitly specified in ionic form, to the extent possible; otherwise such counterions may be freely selected, except for avoiding counterions that act adversely to the objects of the invention); and the term “mole” and its variations may be applied to elemental, ionic, and any other chemical species defined by number and type of atoms present, as well as to compounds with well defined molecules.
The term “aluminum” when used hereinafter, unless the context requires otherwise, is to be understood to include pure aluminum and all the alloys of aluminum that contain at least 45% of aluminum by weight.
SUMMARY OF THE INVENTION
One embodiment of the invention is an aqueous liquid composition that, in addition to water, comprises, preferably consists essentially of, or more preferably consists of, the following dissolved, stably dispersed, or both dissolved and stably dispersed components:
(A) a concentration of a component of alkali metal borate salts;
(B) a concentration of boric acid in excess of any generated by reaction of anions of component (A) with water;
(C) a concentration of a component of nonionic surfactant; and
(D) a concentration of a component selected from the group consisting of anionic and amphoteric surfactants; and, optionally, one or more of:
(E) a concentration of a component of salts that are not part of any of the previously recited components;
(F) a component of organic compounds that are not part of any of the previously recited components and are liquid at 25° C.;
(G) a component of hydrotroping agent that is not part of any of the previously recited components; and
(H) a component of organic corrosion inhibitors that are not part of any of the previously recited components.
In this description, “stably dispersed” means that the component so described can be dispersed by mixing, within 1 hour of its introduction into the liquid phase in which the component in question is described as stably dispersed, to produce a liquid mixture which has only one bulk phase detectable with unaided normal human vision and does not spontaneously develop any separate bulk phase detectable with normal unaided human vision within 24 hours, or preferably, with increasing preference in the order given, within 7, 30, 60, 90, 120, 180, 240, 300, or 360 days, of storage without mechanical agitation at 25° C. after being initially mixed. (The word “bulk” in the preceding sentence means that, to be considered as a bulk phase, a phase must occupy at least one volume of space that is sufficiently large to be visible with unaided normal human vision and is separated from at least one other phase present in the dispersion by a boundary surface that can be observed with unaided normal human vision. Therefore, a change of the composition from clear to hazy or from hazy to clear does not indicate instability of a dispersion within this definition, unless a separate liquid or solid phase develops in the mixture in at least one volume large enough to see independently with unaided normal human vision.) Also in this description, “alkali stable” when referring to a surfactant means that the surfactant is capable of coexisting at its critical micelle concentration in an aqueous solution also containing at least, with increasing preference in the order given, 5, 10, 15, 20, 25, or 29% sodium hydroxide, without any chemical reaction (except possibly for reversible neutralizatio
Carlson Lawrence R.
Pierce John R.
Deluca Peter
Gupta Yogendra N.
Harper Stephen D.
Henkel Corporation
Jaeschke Wayne C.
LandOfFree
Composition and method for cleaning/degreasing metal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition and method for cleaning/degreasing metal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition and method for cleaning/degreasing metal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526344